Circulating water scoop



Patented Oct. 27, 1936 PATENT OFFICE CIRGULATING WATER soooP Alexander I. Ponomarefi',

Ridley Park, Pa.,

assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 19, 1936, Serial No. 64,646

3 Claims.

My invention relates to scoops for circulating condensing water through marine condensers and it has for an object to provide apparatus of this character which shall serve with improved effi 5 ciency when the ship is operating astern.

. As pointed outin' my application, Serial'No;

23,530, now Patent No. 2,025,008, Mar. 24 1936, filed May 25, 1935, a loss in suction head is encountered where scoops are used and the ship is operated astern unlessspecial avoidance measures are taken. In that application the scoop is provided with a lip which protrudes from the skin of the ship at the after side of the scoop inlet and a deflector; is arranged aft of the lip, the deflector serving to cause flow lines in the water which make entrance of such water into the scoop easier when the ship is operating astern with the result that the head loss is decreased.

In the patent to Henry F. Schmidt, No. 1,893,039, granted January 3, 1933, there is disclosed and claimed a divergent type of scoop which preferably has its inlet entirely flush with the skin of the ship. Upon reference to this patent, it will be seen that the after side of the scoop inlet is defined by a structure whose crosssection is an acute angle. Observations as to performance of this type of scoop indicate that, while deliveringthe necessary quantity of circulatingwater during'ahead operation of the ship, the scoop is responsible for an undesirable loss of head during'astern operation. The loss of head'during astern operation may be conveniently expressed by the formula:

g=acceleration due to gravityft./sec

This loss occurs, due to the fact that, to enter the scoop when going astern, water at high velocity must change its direction through an angle of more than 90; and, if no provision is made to facilitate the change in direction there is a considerable eddy loss at the after side of the scoop entrance, which is conducive to the loss in head. Accordingly, an object of the present invention is to round the after side of the scoop inlet to promote easy turning and entrance of water when the ship is operated astern in order to reduce the head loss.

Expressing the radius of rounding of the after side of the scoop'inlet in terms of percentage of the scoop height, then the performance is improved as the radius is made larger up to a certain extent, it being apparent that the radius should not be so large as to adversely affect the design of the scoop but it should be sufficient to secure the most beneficial operation. I have found that the optimum value of the radius of rounding is from about to of the scoop height at the entrance. Accordingly, a further object of my invention is to provide a divergent scoop having a rounded after side wherein the radius is from 10 to 15% of the scoop height.

These and other objects are effected by my invention as Will be apparent from the following description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. l is a view showing a scoop incorporating my improvement and wherein the scoop is shown in relation to portions of the ship and of the condenser;

Fig. 2 is a sectional view of a divergent type of scoop diagrammatically indicating stream lines and eddies involved with astern operation;

Fig. 3 is a View similar to Fig. 2 but showing the effect of rounding of the after side of the entrance on the stream lineswhen operating astern; and,

' Figs. 4, 5, and 6 are diagrams indicating the respects in which operation is improved by rounding of the after side.

Referring now, more particularly, to Fig. 1, I show amarine condenser in having circulating water supplied thereto by means of a scoop II when the ship is operated in the ahead direction indicated by the arrow.

The'scoop ll supplies water through the conduit I3 to the inlet water box M. A pump I5 is associated with the conduit and it assures flow of cooling water when the ship is propelled at low speeds or when operating astern.

1. The scoop i i has its inlet ll flush with the exterior of the ship as disclosed and claimed in the aforesaid patent to Schmidt, and it will be noted that the scoop includes an inlet portion which is inclined forwardly and toward the skin of the ship so that its axis defines, with the surface of the ship, an acute angle. With this type of divergent scoop, therefore, the after side of the inlet was defined by a structure of acute-angled section.

As indicated in Fig. 2, when operating astern with a divergent scoop having an after side coming out to a sharp edge, there is a considerable turning loss incident to water entering the scoop, this loss being due to the fact that water at high velocity must change its direction through an angle of more than The structure would call for a sudden or abrupt change in direction, but the high velocity water cannot accommodate itself to the structure with the result that the stream lines extend around the after edge and forwardly of the after side of the scoop, resulting in a restricted effective flow area and a space wherein considerable losses are encountered because of eddying.

In accordance with my invention, the aforementioned head loss incident to astern operation is reduced by structural modification given to the after side of the scoop at the inlet, such side being rounded, as shown in Figs. 1 and 3, with the result that the water may enter the scoop and undergo gradual changes in direction with some reduction in the total angle through which the water is turned. The rounded after side, therefore, provides a structure which is more nearly in accordance with the directions of flow which the water naturally tends to assume, that is, the entering stream lines gradually turn about the rounded after side without undue formation of eddies. From a mathematical point of view, the improvement incident to rounding is, therefore, due to two things; namely, (1) reduction in the total angle through which the entering water is turned, and (2) accommodation of the structure to the inevitable gradual turning which must take place.

Rounding of the after side of the scoop at the inlet should be suflicient to secure the most beneficial operation, but it should not be so great as to adversely alfect the design of the scoop in other respects. The extent of rounding, or the radius, is conveniently expressed in terms of the ratio of such radius to the scoop height or throat distance at the inlet. In Fig. 4, there are shown three curves, A, B, and C, curve A showing the coefiicient of scoop loss with reference to rate of flow of circulating water, such loss increasing with diminishing rate of flow. Curve B represents the improvement secured by rounding the after side using a radius of 8% of the scoop throat height. Curve C shows a still further improvement, if a somewhat larger radius of rounding is used, curve C being for a radius of 13% of the scoop throat height. It will be noted that curve C, particularly with increasing circulating water rates, approaches the coefiicient of unity so that this extent of rounding approaches the maximum improvement that can be secured.

Figs. 5 and 6 are graphs showing the beneficial effects of an after side rounded with a radius of 13% of the scoop throat height as compared to a scoop having a sharp edged after side. In Fig. 5, it will be seen that the rounded arrangement reduces to a very substantial extent the suction lift required when operating astern, and Fig. 6 indicates, by the dash line, the reduced total head involved with a radius of 13%. In view of the experiments forming the basis of the graphs shown in Figs. 4, 5, and 6, it will be apparent that rounding of the after side even to a very small radius is beneficial, improved operation being secured as the radius is made larger, almost the maximum of improvement having been secured with a radius of 13% of the throat height. Therefore, in acocrdance with my invention, I prefer to use a radius of from 10 to 15% of the throat height.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is: i

1. The combination with a ship having a skin and a condenser for its power plant, the condenser having an inlet water box, of circulating water supply conduit means communicating with the inlet water box, a scoop connected to said conduit means and having its inlet end flush with the skin of the ship, said scoop including an inlet portion inclined forwardly toward the skin of the ship so that its axis defines an acute angle with respect thereto and being effective, when the ship is going ahead above a predetermined speed, to cause fiow of water through the conduit means and the condenser, and a pump associated with the conduit means to assure adequate flow when operating astern, said inlet portion of the scoop having its after side at the entrance rounded for reducing the head loss of the pump so as to facilitate circulation when operating astern.

2. The combination of a ship having a skin and a condenser for its power plant, the condenser having an inlet water box, a circulating water supply conduit means communicating with the inlet water box, a scoop connected to said conduit means and having its inlet end flush with the skin of the ship, said scoop including an inlet portion which is inclined forwardly with respect to the skin of the ship so that its axis defines an acute angle with respect thereto and effective, when the ship is going ahead above a predetermined speed, to cause flow of water through the conduit means and the condenser, and a pump associated with the conduit means to assure adequate flow when operating ahead below said predetermined speed and when operating astern, the interior surface of the scoop inlet portion at the after side thereof and the exterior surface of the ship including structure which is rounded in order to avoid an acute-angled structure at such after side, said rounding reducing the head loss as to facilitate circulation when operating astern.

3. The combination as claimed in claim 1 wherein the radius of rounding is from 10 to 15% of the throat height at the entrance.

ALEXANDER I. PONOMAREFF. 

